Abstract:

A manipulator is provided with an arm, an arm, a holding section, a first
joint section pivotally interconnecting the arm and the arm, a second
joint section pivotally interconnecting the arm and the holding section,
a first joint driving section capable of driving the first joint section,
a second joint driving section capable of driving the second joint
section, a member specifying section for specifying one of the arms which
has a possibility of collision with an obstacle or which has collided
with the obstacle, and a control device for controlling the first joint
driving section and the second joint driving section to pivotally move
the one of the arms specified by the member specifying section in a
direction away from the obstacle, and pivotally move the other of the
arms in a direction toward the obstacle.

Claims:

1-12. (canceled)

13. A manipulator comprising:a first movable member;a second movable
member;a holding section;a first joint section pivotally interconnecting
the first movable member and the second movable member;a second joint
section pivotally interconnecting the second movable member and the
holding section;a first joint driving section capable of driving the
first joint section;a second joint driving section capable of driving the
second joint section;a member specifying section for specifying one of
the first movable member and the second movable member which has a
possibility of collision with an obstacle, or which has collided with the
obstacle; anda control device for controlling the first joint driving
section and the second joint driving section in such a manner as to
pivotally move the one movable member specified by the member specifying
section in a direction away from the obstacle, and pivotally move the
other movable member in a direction toward the obstacle.

14. The manipulator according to claim 13, whereinthe control device
includes an acceleration determining section for determining whether or
not the pivotal movement of the other movable member is to be
accelerated, based on positional relation information representing a
positional relation between the one movable member specified by the
member specifying section, and the obstacle, angle information
representing an angle defined by the first movable member and the second
movable member, and pivotal direction information representing a pivotal
direction of the other movable member.

15. The manipulator according to claim 14, whereinthe acceleration
determining section determines, based on the positional relation
information, the angle information, and the pivotal direction
information, that the pivotal movement of the other movable member is to
be accelerated, in the case where the obstacle is in a direction opposite
to a direction of a reaction force generated on the one movable member by
acceleration of the pivotal movement of the other movable member, and
that the pivotal movement of the other movable member is not to be
accelerated, in the case where the obstacle is in the direction of the
reaction force.

16. The manipulator according to claim 15, whereinassuming a direction of
pivotally moving the other movable member about an axis of pivotal
movement of the first joint section is a positive direction, and the
angle defined by the first movable member and the second movable member
is θ, and in the case where the other movable member is pivotally
moved in the pivotal direction, the acceleration determining
section:determines that the pivotal movement of the other movable member
is to be accelerated, in the case where a condition:
0.degree.<θ<90.degree. or
270.degree.<θ<360.degree. is satisfied, and the obstacle is
in a direction of decreasing the angle θ;determines that the
pivotal movement of the other movable member is not to be accelerated, in
the case where a condition: 0.degree.<θ<90.degree. or
270.degree.<θ<360.degree. is satisfied, and the obstacle is
in a direction of increasing the angle θ;determines that the
pivotal movement of the other movable member is to be accelerated, in the
case where a condition: 90.degree.<θ<180.degree. or
180.degree.<θ<270.degree. is satisfied, and the obstacle is
in a direction of increasing the angle θ; anddetermines that the
pivotal movement of the other movable member is not to be accelerated, in
the case where a condition: 90.degree.<θ<180.degree. or
180.degree.<θ<270.degree. is satisfied, and the obstacle is
in a direction of decreasing the angle θ.

17. The manipulator according to claim 13, whereinthe holding section
includes a moving section configured to hold the second movable member
and be movable by a moving/driving section, andthe control device
controls the moving/driving section to move the moving section in a
direction away from the obstacle, in the case where the one movable
member is the first movable member, and move the moving section in a
direction toward the obstacle, in the case where the one movable member
is the second movable member.

18. The manipulator according to claim 13, whereinthe member specifying
section derives a position of the obstacle based on photographed images
obtained by at least two photographing sections, and specifies one of the
first movable member and the second movable member which has a
possibility of collision with the obstacle, or which has collided with
the obstacle.

19. A manipulator comprising:a first movable member;a second movable
member;a first joint section pivotally interconnecting the first movable
member and the second movable member;a moving section including a
moving/driving section;a third joint section pivotally interconnecting
the second movable member and the moving section;a first joint driving
section capable of driving the first joint section;a third joint driving
section capable of driving the third joint section;a member specifying
section for specifying one of the first movable member and the second
movable member which has a possibility of collision with an obstacle, or
which has collided with the obstacle; anda control device for controlling
the first joint driving section, the third joint driving section, and the
moving/driving section in such a manner as to pivotally move the one
movable member specified by the member specifying section in a direction
away from the obstacle, move the moving section in the direction away
from the obstacle, in the case where the one movable member is the first
movable member, and move the moving section in a direction toward the
obstacle, in the case where the one movable member is the second movable
member.

20. The manipulator according to claim 19, whereinthe control device
includes an acceleration determining section for determining whether or
not the moving section is to be accelerated, based on positional relation
information representing a positional relation between the one movable
member specified by the member specifying section, and the obstacle, and
angle information representing an angle defined by the first movable
member and the second movable member.

21. The manipulator according to claim 20, whereinthe acceleration
determining section determines, based on the positional relation
information and the angle information, that the moving section is to be
accelerated, in the case where the obstacle is in a direction opposite to
a direction of a reaction force generated on a centroid of the one
movable member by acceleration of the moving section, and that the moving
section is not to be accelerated, in the case where the obstacle is in
the direction of the reaction force.

22. A method of controlling a manipulator provided with a first movable
member, a second movable member, a holding section, a first joint section
pivotally interconnecting the first movable member and the second movable
member, a second joint section pivotally interconnecting the second
movable member and the holding section, a first joint driving section
capable of driving the first joint section, and a second joint driving
section capable of driving the second joint section, the method
comprising:a member specifying step of specifying one of the first
movable member and the second movable member which has a possibility of
collision with an obstacle, or which has collided with the obstacle; anda
controlling step of controlling the first joint driving section and the
second joint driving section in such a manner as to pivotally move the
one movable member specified in the member specifying step in a direction
away from the obstacle, and pivotally move the other movable member in a
direction toward the obstacle.

23. The method of controlling the manipulator according to claim 22,
whereinin the controlling step, the other movable member is determined to
be accelerated, in the case where the obstacle is in a direction opposite
to a direction of a reaction force generated on the one movable member by
acceleration of the pivotal movement of the other movable member, and the
other movable member is determined not to be accelerated, in the case
where the obstacle is in the direction of the reaction force.

24. A method of controlling a manipulator provided with a first movable
member, a second movable member, a moving section including a
moving/driving section, a first joint section pivotally interconnecting
the first movable member and the second movable member, a third joint
section pivotally interconnecting the second movable member and the
moving section, a first joint driving section capable of driving the
first joint section, and a third joint driving section capable of driving
the third joint section, the method comprising:a member specifying step
of specifying one of the first movable member and the second movable
member which has a possibility of collision with an obstacle, or which
has collided with the obstacle; anda controlling step of controlling the
first joint driving section, the third joint driving section, and the
moving/driving section in such a manner as to pivotally move the one
movable member specified in the member specifying step in a direction
away from the obstacle, move the moving section in the direction away
from the obstacle, in the case where the one movable member is the first
movable member, and move the moving section in a direction toward the
obstacle, in the case where the one movable member is the second movable
member.

Description:

TECHNICAL FIELD

[0001]The invention relates to a manipulator and a method of controlling
the same.

RELATED ART

[0002]There has been made various proposals on the technology of avoiding
collision with an obstacle.

[0003]For instance, in a conventional manipulator disclosed in patent
literature 1, a camera is disposed at a distal end of a multi-articulate
structural body to photograph an image near the distal end of the
manipulator, and the posture of the manipulator is controlled in such a
manner as to avoid collision with an obstacle, if the obstacle is
detected.

[0004]In the conventional manipulator, in the case where an obstacle is
detected in controlling the posture of the manipulator, the direction of
a current flowing to a motor in a driving section for driving a movable
member is inverted to apply a reverse torque to an aim. Collision with
the obstacle is avoided by the reverse torque. Generally, in a
manipulator, a speed reducing mechanism is provided in an output section
of a motor to apply a driving torque, and the rotation number of the
motor is set to a relatively large value while the motor is driven. As a
result, a time required from a point of time when the motor starts
decelerating to a point of time when a reverse torque is applied tends to
increase. Specifically, there is a problem in the conventional
manipulator that responsiveness in avoiding collision or applying a
reverse torque to avoid collision may be insufficient, because a time
required until a movable member starts moving in a reverse direction is
relatively long.

Patent Literature 1: JP Hei 9-207089A

SUMMARY OF THE INVENTION

[0005]In view of the above, an object of the invention is to provide a
manipulator that enables to promptly drive a movable member in a reserve
direction, and a method of controlling the manipulator.

[0006]A manipulator according to an aspect of the invention includes a
first movable member; a second movable member; a holding section; a first
joint section pivotally interconnecting the first movable member and the
second movable member; a second joint section pivotally interconnecting
the second movable member and the holding section; a first joint driving
section capable of driving the first joint section; a second joint
driving section capable of driving the second joint section; a member
specifying section for specifying one of the first movable member and the
second movable member which has a possibility of collision with an
obstacle, or which has collided with the obstacle; and a control device
for controlling the first joint driving section and the second joint
driving section in such a manner as to pivotally move the one movable
member specified by the member specifying section in a direction away
from the obstacle, and pivotally move the other movable member in a
direction toward the obstacle.

[0007]A manipulator according to another aspect of the invention includes
a first movable member; a second movable member; a first joint section
pivotally interconnecting the first movable member and the second movable
member; a moving section including a moving/driving section; a third
joint section pivotally interconnecting the second movable member and the
moving section; a first joint driving section capable of driving the
first joint section; a third joint driving section capable of driving the
third joint section; a member specifying section for specifying one of
the first movable member and the second movable member which has a
possibility of collision with an obstacle, or which has collided with the
obstacle; and a control device for controlling the first joint driving
section, the third joint driving section, and the moving/driving section
in such a manner as to pivotally move the one movable member specified by
the member specifying section in a direction away from the obstacle, move
the moving section in the direction away from the obstacle, in the case
where the one movable member is the first movable member, and move the
moving section in a direction toward the obstacle, in the case where the
one movable member is the second movable member.

[0008]A method of controlling a manipulator according to yet another
aspect of the invention is a method of controlling a manipulator provided
with a first movable member, a second movable member, a holding section,
a first joint section pivotally interconnecting the first movable member
and the second movable member, a second joint section pivotally
interconnecting the second movable member and the holding section, a
first joint driving section capable of driving the first joint section,
and a second joint driving section capable of driving the second joint
section. The method includes a member specifying step of specifying one
of the first movable member and the second movable member which has a
possibility of collision with an obstacle, or which has collided with the
obstacle; and a controlling step of controlling the first joint driving
section and the second joint driving section in such a manner as to
pivotally move the one movable member specified in the member specifying
step in a direction away from the obstacle, and pivotally move the other
movable member in a direction toward the obstacle.

[0009]A method of controlling a manipulator according to still another
aspect of the invention is a method of controlling a manipulator provided
with a first movable member, a second movable member, a moving section
including a moving/driving section, a first joint section pivotally
interconnecting the first movable member and the second movable member, a
third joint section pivotally interconnecting the second movable member
and the moving section, a first joint driving section capable of driving
the first joint section, and a third joint driving section capable of
driving the third joint section. The method includes a member specifying
step of specifying one of the first movable member and the second movable
member which has a possibility of collision with an obstacle, or which
has collided with the obstacle; and a controlling step of controlling the
first joint driving section, the third joint driving section, and the
moving/driving section in such a manner as to pivotally move the one
movable member specified in the member specifying step in a direction
away from the obstacle, move the moving section in the direction away
from the obstacle, in the case where the one movable member is the first
movable member, and move the moving section in a direction toward the
obstacle, in the case where the one movable member is the second movable
member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a schematic construction diagram of a manipulator in
accordance with a first embodiment of the invention.

[0011]FIG. 2 is a block diagram showing an arrangement of the manipulator.

[0012]FIGS. 3A and 3B are schematic front views showing a first example of
a collision avoiding operation to be performed by the manipulator.

[0013]FIGS. 4A and 4B are schematic front views showing a second example
of a collision avoiding operation to be performed by the manipulator.

[0014]FIG. 5 is a diagram for describing an acceleration determining
condition by an acceleration determining section of the manipulator.

[0015]FIGS. 6A through 6D are diagrams for describing a direction of a
reaction force component which contributes to rotation of a movable
member of the manipulator.

[0016]FIG. 7 is a flowchart for describing an obstacle avoiding operation
to be performed by the manipulator.

[0017]FIG. 8 is a schematic construction diagram of a manipulator in
accordance with a second embodiment of the invention.

[0018]FIG. 9 is a block diagram showing an arrangement of the manipulator
in the second embodiment.

[0019]FIGS. 10A and 10B are schematic front views showing a first example
of a retracting operation to be performed by the manipulator in the
second embodiment.

[0020]FIGS. 11A and 11B are schematic front views showing a second example
of a retracting operation to be performed by the manipulator in the
second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0021]In the following, embodiments of the invention will be described in
detail referring to the drawings.

First Embodiment

[0022]Firstly, an arrangement of a manipulator in accordance with the
first embodiment of the invention is described referring to FIG. 1. FIG.
1 is a schematic construction diagram of the manipulator 1 in accordance
with the first embodiment of the invention.

[0023]The manipulator 1 includes a movable section 91, and a holding
section 8 for holding the movable section 91. The movable section 91 has
a hand 2 as a movable member, an arm 4 as a movable member, and an arm 6
as a movable member. Alternatively, the movable section 91 may have at
least two movable members (a first movable member and a second movable
member). For instance, the movable section 91 may have only of the hand 2
and the arm 4, or only of the arm 4 and the arm 6, or may be
interconnected to another movable member.

[0024]The hand 2 has a function of gripping an object, and is
interconnected to a distal end of the arm 4 through a joint section 3. A
base end of the arm 4 is interconnected to a distal end of the arm 6
through a joint section 5. A base end of the arm 6 is interconnected to
the holding section 8 through a joint section 7. The hand 2, the arm 4,
and the arm 6 are pivotally interconnected to each other. A pivot shaft
of the joint section 5, and a pivot shaft of the joint section 7 are
aligned in parallel to each other in a direction perpendicular to the
plane of FIG. 1.

[0025]The holding section 8 includes a mechanism section 81 and a driving
section 82. The mechanism section 81 has photographing sections 11 and 12
operable to photograph an image of the movable section 91. The
photographing sections 11 and 12 are also operable to photograph an image
of an obstacle 9 which may collide the movable section 91. The driving
section 82 has an input section 21 for allowing a user to input an
operation command, a collision monitoring section 23 for monitoring
collision with the obstacle 9, and a control device 22 for controlling
joint driving sections (actuators 31, 51, and 71 to be described later)
to drive the hand 2, the arm 4, and the arm 6. The photographing sections
11 and 12 output photographed images to the collision monitoring section
23. The control device 22 controls the joint driving sections, based on
operation command information acquired from the input section 21, and
monitor information acquired from the collision monitoring section 23.

[0026]In this example, the photographing sections 11 and 12 are provided
in the mechanism section 81. Alternatively, the photographing sections 11
and 12 may be provided independently of the mechanism section 81 (for
instance, the photographing sections 11 and 12 may be disposed in the
peripheral environment where the entirety of the manipulator 1 is
viewable).

[0027]Next, a construction and an operation of the manipulator 1 are
described referring to FIG. 2. FIG. 2 is a block diagram showing a
construction of the manipulator 1 in accordance with the first embodiment
of the invention.

[0028]The joint sections 3, 5, and 7 respectively have the actuators 31,
51, and 71 as the joint driving sections. The actuator 31 drives the hand
2 to rotate the hand 2 with respect to the arm 4 through a speed reducer
38. Similarly, the actuator 51 drives the arm 4 to rotate the arm 4 with
respect to the arm 6 through a speed reducer 38. The actuator 71 drives
the arm 6 to rotate the arm 6 with respect to the holding section 8
through a speed reducer 38. Each of the speed reducers 38 reduces the
rotation of a corresponding motor 34 to be described later by a gear or a
like member, and increases a driving torque of the actuator 31, 51, 71.
The speed reducers 38 further have a function as a power transmission
mechanism for transmitting driving forces of the actuators 31, 51, and 71
to the hand 2, the arm 4, and the arm 6, respectively. Examples of the
speed reducer 38 are a planetary gear speed reducer, a spur gear speed
reducer, and a belt-driven speed reducing mechanism.

[0029]Each of the actuators 31, 51, and 71 includes a driving motor 34, a
motor driver 35 for driving the motor 34, and an encoder 36.

[0030]The motor driver 35 has a drive circuit such as an H-bridge drive
circuit, and supplies an electric power to the motor 34 by the drive
circuit to rotate the motor 34 in forward and backward directions.

[0031]The encoder 36 is configured to be coupled to a shaft (not shown) of
the motor 34 to detect rotation information of the motor 34. Examples of
the encoder 36 are an optical encoder comprising of a coding plate and a
photodetector; and a magnetic encoder comprising of a hall element or a
magnetic resistor element, and a rotary magnet having a north pole and a
south pole.

[0032]The input section 21 has an unillustrated input device. The input
section 21 outputs, to the control device 22, an operation command
inputted through the input device. Examples of the input device are a key
input device, a joystick, and a touch panel. In the example shown in FIG.
1, the input section 21 is housed in the holding section 8.
Alternatively, the input section 21 may be configured to be detachably
attached to the holding section 8, or may be configured to be an
independent unit. Further alternatively, in the case where the
manipulator 1 is configured to be movable by itself, the input section 21
may be configured to receive an operation command inputted from an
external device such as a high-order control device (not shown).

[0033]The collision monitoring section 23 analyzes two images photographed
by the photographing sections 11 and 12, and monitors e.g. movement
information of the obstacle 9 including distance/direction information
detected through stereoscopic viewing, and positional relation
information representing e.g. a positional relation between the obstacle
9 and the movable section 91. The collision monitoring section 23
determines whether or not there is a possibility of collision between the
obstacle 9 and the movable section 91. In the case where the collision
monitoring section 23 has determined that there is a possibility of
collision between the obstacle 9 and the movable section 91, a movable
member (e.g. the arm 4) of the movable section 91 having a possibility of
collision is specified; and information (movement information and
position information) of the obstacle 9, and position information of the
movable member having a possibility of collision are outputted to the
control device 22, as monitor information. Alternatively, the function of
the collision monitoring section 23 may be provided as a function of the
control device 22. In this example, a stereo camera method utilizing a
parallax between the photographing sections 11 and 12 is used as means
for monitoring e.g. a movement of the obstacle 9 including
distance/direction information, and a positional relation between the
obstacle 9 and the movable section 91. The embodiment is not limited to
the above. For instance, there may be used a distance image sensor
constructed in such a manner that a time of flight required for light
emitted from a light emitting diode to return to a CCD (Charge Coupled
Device) by reflection on a target measurement object is measured, and a
distance from an image of the target measurement object to the target
measurement object is outputted pixel by pixel by superimposing image
information.

[0034]The control device 22 includes a central processing unit (CPU) for
executing various functions based on a program, a read only memory (ROM)
storing various programs and the like, a random access memory (RAM) for
temporarily storing data, and an input/output section for allowing
input/output of data with respect to an external device. The control
device 22 having the above configuration executes various programs based
on an operation command acquired from the input section 21 and monitor
information acquired from the collision monitoring section 23 to thereby
control and drive the actuator 31, 51, 71 to perform a collision avoiding
operation, in the case where there is a possibility of collision between
the movable section 91 and the obstacle 9. Further, the control device 22
is operable to detect positions and postures of the hand 2, the arm 4,
and the arm 6, and respective angles between the movable members, based
on rotation information of the motors 34 acquired from the encoders 36.
Furthermore, the control device 22 is operable to acquire information
(pivotal direction information) relating to a pivotal direction of a
movable member (e.g. the arm 6) different from the movable member (e.g.
the arm 4) specified by the collision monitoring section 23, based on
rotation direction information of the motors 34 acquired from the
encoders 36.

[0035]The control device 22 is further provided with an acceleration
determining section 25. The acceleration determining section 25
determines whether or not the manipulator 1 is to be accelerated in
performing a collision avoiding operation between the obstacle 9 and the
movable section 91. The acceleration determining section 25 will be
described later.

[0036]Next, a collision avoiding operation to be performed by the
manipulator 1 with respect to the obstacle 9 is described referring to
FIG. 2, and FIGS. 3A through 4B. FIGS. 3A and 3B are schematic front
views showing a first example of a collision avoiding operation to be
performed by the manipulator 1 in accordance with the first embodiment.
FIGS. 4A and 4B are schematic front views showing a second example of a
collision avoiding operation to be performed by the manipulator 1 in
accordance with the first embodiment.

[0037]Firstly, the first example of a collision avoiding operation to be
performed by the manipulator 1 is described referring to FIGS. 2 through
3B.

[0038]The control device 22 drives the actuator 31, 51, 71 in accordance
with an operation command from the input section 21, and acquires monitor
information from the collision monitoring section 23. The control device
22 starts an operation of moving a movable member in such a direction as
to avoid collision with the obstacle 9, based on e.g. information
relating to the position/posture of a movable member (the hand 2, or the
arm 4, or the arm 6) of the movable section 91 having a possibility of
collision, information relating to the position/posture of the other
movable member(s), and driving information (including pivotal direction
information) of the joint section 3, 5, 7, in the case where a
possibility of collision between the obstacle 9 and the movable section
91 is detected based on the monitor information. Specifically, the
control device 22 generates control information for moving a movable
member in such a direction as to avoid collision with the obstacle 9,
drives the actuator 31, 51, 71 based on the control information, and
controls the joint section 3, 5, 7 to pivotally move the joint section 3,
5, 7.

[0039]For instance, the manipulator 1 drives the actuator 31, 51, 71 in
accordance with an operation command from the input section 21. For
instance, the manipulator 1 suspends an operation of the actuator 31, and
drives the actuators 51 and 71 in accordance with an operation command.

[0040]As a result of the above operation, for instance, as shown in FIG.
3A, the manipulator 1 pivotally moves the arm 4 in the direction of arrow
A about an axis of rotation of the joint section 5, and pivotally moves
the arm 6 in the direction of arrow A about an axis of rotation of the
joint section 7. In other words, the direction of pivotally moving the
arm 6, and the direction of pivotally moving the arm 4 are identical to
each other with respect to the joint section 7.

[0041]In response to the pivotal movement, for instance, in the case where
there is a possibility of collision between the obstacle 9 and the arm 4,
the collision monitoring section 23 is activated, and outputs monitor
information. The monitor information is inputted to the control device
22.

[0042]The control device 22 controls the actuators 51 and 71 to drive the
actuators 51 and 71 based on the monitor information, after having
detected a possibility of collision between the arm 4 and the obstacle 9.
Specifically, the actuator 51 drives the arm 4 with a rotation torque in
a direction opposite to the direction of arrow A, and the actuator 71
accelerates the pivotal movement of the arm 6 by increasing a rotation
torque, without changing the pivotal direction of the arm 6. In other
words, the manipulator 1 accelerates and pivotally moves the arm 6 in a
collision direction with respect to the obstacle 9, while pivotally
moving the arm 4 with respect to the arm 6 in a collision avoiding
direction (the direction of arrow B in FIG. 3B) with respect to the
obstacle 9.

[0043]As shown in FIG. 3B, in response to acceleration of the pivotal
movement of the arm 6 in the direction of arrow A about an axis of
rotation of the joint section 7, the base end of the arm 4 is accelerated
in the direction of arrow A. As a result of the above operation, a
reaction force (a rotary moment) by an inertia force is acted on a
centroid position 4a of the arm 4. The reaction force is acted in such a
way as to pivotally move the arm 4 in the direction of arrow B about the
axis of rotation of the joint section 5. Specifically, accelerating the
pivotal movement of the arm 6 by the reaction force enables to assist an
operation of reversing the pivotal movement of the arm 4. In the above
arrangement, since a rotary moment in a direction opposite to the
collision direction is acted on the arm 4, despite that the pivotal
movement of the arm 6 is accelerated in the collision direction with
respect to the obstacle 9, the posture of the arm 4 is promptly shifted
in the direction of arrow B. In other words, the arm 4 is moved in a
direction away from the obstacle 9.

[0044]As a result of the above operation, the manipulator 1 is operable to
drive the arm 4 to pivotally move the arm 4 in the direction of arrow B,
with a reaction force by an inertia force being acted, in addition to a
rotation torque of the actuator 51. Accordingly, it is possible to
promptly move the arm 4 in such a direction to avoid collision with the
obstacle 9.

[0045]Further, the movable section 91 is driven to be bent toward the
holding section 8 depending on a posture of the arm 6. This enables to
more securely avoid collision of the arm 4 with the obstacle 9.

[0046]As described above, the manipulator 1 is operable to drive the arm 4
to pivotally move the arm 4 in the collision avoiding direction by
utilizing a reaction force in addition to a rotation torque of the
actuator 51, by accelerating the pivotal movement of the arm 6 without
changing the pivotal direction of the arm 6. This enables to promptly
avoid collision of the arm 4 with the obstacle 9.

[0047]As described above, it is possible to promptly avoid collision of
the arm 4 with the obstacle 9, since a reaction force is utilized in this
embodiment, even if a mechanical/electrical time constant of the actuator
51 is large, or even if a driving force of the actuator 51 is small.

[0048]Next, a second example of a collision avoiding operation is
described referring to FIGS. 4A and 4B.

[0049]In the first example, a reaction force is generated in a direction
(the direction of arrow B in FIG. 3B) of reversing the pivotal movement
of the arm 4 by accelerating the pivotal movement of the arm 6 in the
direction of arrow A in FIGS. 3A and 3B. In the second example, a
reaction force is generated by moving the joint section 7 serving as a
center of pivotal movement of the arm 6.

[0050]The holding section 8 of the manipulator 1 includes a holding
section main body 8a, and a moving section 13 for moving the movable
section in parallel to the holding section main body 8a. Collision is
avoided by using the moving section 13.

[0051]The moving section 13 is a member designed to be slidably movable in
a predetermined direction relative to the holding section main body 8a of
the holding section 8. An example of the moving section 13 is a
rectilinear slider. Since the joint section 7 is supported on the moving
section 13, the moving section 13 is operable to move the movable section
91 in parallel to the direction of arrow D in FIG. 4B. The moving section
13 includes a moving/driving section 14. The moving/driving section 14
has a motor (not shown), a speed reducer (not shown), a driver (not
shown) for driving the motor, and is controlled by the control device 22.
The arm 6 is pivotally interconnected to the moving section 13 through
the joint section 7. It is desirable to align the moving direction of the
moving section 13 with a direction perpendicular to the pivot shaft of
the joint section 7 in order to securely generate a reaction force by
moving the moving section 13. Alternatively, in the case where a moving
range of the moving section 13 is restricted depending on e.g. the
construction of the holding section 8, the moving direction of the moving
section 13 may be aligned with a direction other than the above.

[0052]In this example, for instance, as shown in FIG. 4A, a collision
avoiding operation with respect to the obstacle 9 is described by taking
an example, wherein the centroid position 4a of the arm 4 is located, at
a base end (on the side of the mechanism section 81 with respect to X-X
axis) with respect to the joint section 5. In this case, the manipulator
1 performs a collision avoiding operation, based on the positional
relation between the obstacle 9 and the arm 4, and the operation status
of the arm 4, 6 in the second example.

[0053]The manipulator 1 drives the actuator 31, 51, 71 in accordance with
an operation command from the input section 21. For instance, the
manipulator 1 suspends an operation of the actuator 31, and drives the
actuators 51 and 71. Specifically, the manipulator 1 pivotally moves the
arm 4 in the direction of arrow B around the joint section 5, and
pivotally moves the arm 6 in the direction of the arrow A around the
joint section 7.

[0054]In performing the above operation, in the case where there is a
possibility of collision between the obstacle 9 and the arm 4, the
collision monitoring section 23 is activated to output monitor
information to the control device 22. The control device 22 controls the
actuators 51 and 71, and the moving/driving section 14 in such a manner
as to move the arm 4 in a direction of avoiding collision with the
obstacle 9, based on the monitor information.

[0055]Specifically, after having detected a possibility of collision
between the arm 4 and the obstacle 9, the control device 22 controls the
actuator 51 to drive the arm 4 with a rotation torque in a direction (the
direction of arrow A) opposite to the direction of arrow B, and controls
the actuator 71 to drive the arm 6 with a rotation torque in a direction
(the direction of arrow B) opposite to the direction of arrow A. As a
result of the above operation, the pivotal direction of the arm 4 around
the joint section 5 is reversed, and the pivotal direction of the arm 6
around the joint section 7 is also reversed. The control device 22
further drives the moving/driving section 14 in such a manner as to
accelerate the movement of the moving section 13 in the direction of
arrow D from an operation-suspended state. Specifically, the manipulator
1 accelerates the movement of the moving section 13 in the collision
direction with respect to the obstacle 9, while pivotally moving the arm
4 and the arm 6 in reverse directions, respectively.

[0056]As shown in FIG. 4B, in response to acceleration of the movement of
the moving section 13 in the direction of arrow D, the base end of the
arm 6 is accelerated in the direction of arrow D. As a result of the
above operation, a reaction force (a rotary moment) by an inertia force
is acted on the centroid position 4a of the arm 4 in the direction of
arrow E. The reaction force is acted on the arm 4 to pivotally move the
arm 4 in the direction of arrow A about the axis of rotation of the joint
section 5. Similarly, a reaction force by an inertia force is acted on a
centroid position 6a of the arm 6 in the direction of arrow E. As a
result of the above operation, a force for pivotally moving the arm 6
about the axis of rotation of the joint section 7 in the direction of
arrow B is acted on the arm 6. Accordingly, a reaction force by an
inertia force is acted on the centroid position 4a of the arm 4 and the
centroid position 6a of the arm 6 in the direction of arrow E, as an
assisting force for reversing the pivotal movements of the arms 4 and 6,
despite acceleration of the moving section 13 in the collision direction
(the direction of arrow D) with respect to the obstacle 9. This enables
to promptly move the arm 4, which has been specified to have a
possibility of collision with the obstacle 9, in a direction away from
the obstacle 9.

[0057]As described above, the manipulator 1 applies, to the arm 4, a
rotation torque in the reverse direction (collision avoiding direction),
and avoids collision of the arm 4 with the obstacle 9 by utilizing a
reaction force in addition to the rotation torque. This enables to
promptly avoid collision.

[0058]In performing a collision avoiding operation of the arm 4, for
instance, an accelerating operation of the arm 6 and an accelerating
operation of the moving section 13 may be combined, or either one of the
accelerating operations may be performed.

[0059]Next, the acceleration determining section 25 in the control device
22 is described referring to FIG. 5, and FIGS. 6A through 6D. FIG. 5 is a
diagram for describing an acceleration determining condition by the
acceleration determining section 25 in the manipulator 1 in accordance
with the first embodiment of the invention. FIGS. 6A through 6D are
diagrams for describing a direction of a reaction force component
(hereinafter, simply called as a reaction force) which contributes to
pivotal movement of the movable member 2, 4, 6 of the manipulator 1.

[0060]As shown in FIG. 5, the acceleration determining section 25
determines whether or not the manipulator 1 is to be accelerated by an
acceleration determining condition, which is determined based on an angle
θ between the arm 6 and the arm 4, a positional relation between
the arm 4 and the obstacle 9, and a pivotal direction of the arm 6. Then,
if it is determined that the direction of the reaction force acting on
the centroid position 4a of the arm 4 contributes to a collision avoiding
operation, the acceleration determining section 25 outputs a
determination result "ACCELERATE AND PIVOTALLY MOVE". If it is determined
that the direction of the reaction force acting on the centroid position
4a does not contribute to a collision avoiding operation, the
acceleration determining section 25 outputs a determination result "DO
NOT ACCELERATE AND PIVOTALLY MOVE".

[0061]In the following, determination as to whether the manipulator 1 is
to be accelerated is concretely described. As shown in FIG. 5, an
operation example is described, wherein the arm 6 is pivotally moved
clockwise (in the direction of arrow A) with respect to the original
point of absolute coordinate axes Xa and Ya orthogonal to each other, and
the arm 4 is pivotally moved clockwise (in the direction of the arrow A)
with respect to the original point of relative coordinate axes Xb and Yb
orthogonal to each other. As shown in FIG. 5, the original point of the
absolute coordinate axes Xa and Ya is set at the center of rotation of
the joint section 7, and the original point of the relative coordinate
axes Xb and Yb is set at the center of rotation of the joint section 5.
The relative coordinate axis Xb is set in a direction orthogonal to the
longitudinal direction of the arm 6, and the relative coordinate axis Yb
is set in the longitudinal direction of the arm 6.

[0062]In this example, the original point of the relative coordinate axes
Xb and Yb travels on a circumference 20 of a circle having a radius
corresponding to a distance between the original point of the relative
coordinate axes Xb and Yb, and the original point of the absolute
coordinate axes Xa and Ya, with the original point of the absolute
coordinate axes Xa and Ya serving as a center.

[0063]The acceleration determining section 25 determines a direction of a
reaction force acting on the centroid position 4a of the arm 4, based on
the position of the arm 4 in a coordinate system defined by the relative
coordinate axes Xb and Yb; and determines whether the manipulator 1 is to
be accelerated based on the direction of the reaction force, and a
positional relation between the arm 4 and the obstacle 9. Specifically,
the acceleration determining section 25 determines a direction of a
reaction force, in the case where the centroid position of the arm 4 is
in a first region (Xb<0, Yb<0), a second region (Xb<0, Yb>0),
a third region (Xb>0, Yb>0), and a fourth region (Xb>0, Yb<0)
in the coordinate system defined by the relative coordinate axes Xb and
Yb. Then, the acceleration determining section 25 determines whether the
manipulator 1 is to be accelerated, based on the direction of the
reaction force, and a positional relation between the arm 4 and the
obstacle 9. In FIG. 5, the angle θ defined by the arm 6 and the arm
4 is equal to an angle defined by the arm 4 and the arm 6 in the pivotal
direction of the arm 4 as a positive direction with respect to the
centerline of the arm 6 in agreement with a line segment connecting the
centers of pivotal movements of the joint section 5 and the joint section
7. In other words, the angle at which the arm 4 is overlapped with the
arm 6 is set to zero, and the angle, by which the arm 4 is pivotally
moved clockwise in FIG. 5 from the above angular position, is set to
θ.

[0064]Next, a direction of a reaction force acting on the centroid of the
arm 4 in each of the first through the fourth regions is described
referring to FIGS. 6A through 6D.

[0065]FIG. 6A shows an example, wherein the centroid position 4a of the
arm 4 is in the first region. Describing the first region in terms of the
angle θ, the first region is a region where
0°<θ<90°. In this case, a reaction force
exerted on the centroid position 4a of the arm 4 by accelerating the arm
6 is acted in the direction of arrow F. Specifically, a reaction force is
acted in the same direction as the direction of shifting the centroid
position 4a by pivotal movement of the arm 4 in the direction of arrow A.
Accordingly, the acceleration determining section 25 determines
"ACCELERATE AND PIVOTALLY MOVE", in the case where the obstacle 9 is on a
side (i.e. in a direction of decreasing the angle θ) opposite to
the direction of accelerating the pivotal movement of the arm 4 by the
reaction force. This is because the direction of the reaction force
acting on the arm 4 by accelerating the arm 6 is aligned with the
collision avoiding direction. On the other hand, in the case where the
obstacle 9 is in a direction (i.e. in a direction of increasing the angle
θ) of pivotally moving the arm 4 by the reaction force, the
acceleration determining section 25 determines "DO NOT ACCELERATE AND
PIVOTALLY MOVE". This is because, in this case, the reaction force is
acted in the collision direction.

[0066]FIG. 6B shows an example, wherein the centroid position 4a of the
arm 4 is in the second region. Describing the second region in terms of
the angle θ, the second region is a region where
90°<θ<180°. In this case, a reaction force
exerted on the centroid position 4a of the arm 4 by accelerating the arm
6 is acted in the direction of arrow G. Specifically, a reaction force is
acted in a direction opposite to the direction of shifting the centroid
position 4a by pivotal movement of the arm 4 in the direction of arrow A.
Accordingly, the acceleration determining section 25 determines
"ACCELERATE AND PIVOTALLY MOVE", in the case where the obstacle 9 is on a
side (i.e. in a direction of increasing the angle θ) opposite to
the direction of accelerating the pivotal movement of the arm 4 by the
reaction force. This is because the direction of the reaction force
acting on the arm 4 by accelerating the arm 6 is aligned with the
collision avoiding direction. On the other hand, in the case where the
obstacle 9 is in a direction (i.e. in a direction of decreasing the angle
θ) of pivotally moving the arm 4 by the reaction force, the
acceleration determining section 25 determines "DO NOT ACCELERATE AND
PIVOTALLY MOVE". This is because, in this case, the reaction force is
acted in the collision direction.

[0067]FIG. 6C shows an example, wherein the centroid position 4a of the
arm 4 is in the third region. Describing the third region in terms of the
angle θ, the third region is a region where
180°<θ<270°. In this case, a reaction force
exerted on the centroid position 4a of the arm 4 is acted in the
direction of arrow H. Specifically, a reaction force is acted in a
direction opposite to the direction of shifting the centroid position 4a
by pivotal movement of the arm 4 in the direction of arrow A.
Accordingly, the acceleration determining section 25 determines
"ACCELERATE AND PIVOTALLY MOVE", in the case where the obstacle 9 is on a
side (i.e. in a direction of increasing the angle θ) opposite to
the direction of pivotally moving the arm 4 by the reaction force. This
is because the direction of the reaction force acting on the arm 4 by
accelerating the arm 6 is aligned with the collision avoiding direction.
On the other hand, in the case where the obstacle 9 is in a direction
(i.e. in a direction of decreasing the angle θ) of pivotally moving
the arm 4 by the reaction force, the acceleration determining section 25
determines "DO NOT ACCELERATE AND PIVOTALLY MOVE". This is because, in
this case, the reaction force is acted in the collision direction.

[0068]FIG. 6D shows an example, wherein the centroid position 4a of the
arm 4 is in the fourth region. Describing the fourth region in terms of
the angle θ, the fourth region is a region where
270°<θ<360°. In this case, a reaction force
exerted on the centroid position 4a of the arm 4 is acted in the
direction of arrow I. Specifically, a reaction force is acted in the same
direction as the direction of shifting the centroid position 4a by
pivotal movement of the arm 4 in the direction of arrow A. Accordingly,
the acceleration determining section 25 determines "ACCELERATE AND
PIVOTALLY MOVE", in the case where the obstacle 9 is on a side (i.e. in a
direction of decreasing the angle θ) opposite to the direction of
pivotally moving the arm 4 by the reaction force. This is because the
direction of the reaction force acting on the arm 4 by accelerating the
arm 6 is aligned with the collision avoiding direction. On the other
hand, in the case where the obstacle 9 is in a direction (i.e. in a
direction of increasing the angle θ) of pivotally moving the arm 4
by the reaction force, the acceleration determining section 25 determines
"DO NOT ACCELERATE AND PIVOTALLY MOVE". This is because, in this case,
the reaction force is acted in the collision direction.

[0069]Alternatively, the acceleration determining section 25 may memorize
a direction of a reaction force acting on the centroid position of the
arm 4 in each of the first through the fourth regions into a storing
section (not shown), and determine whether the manipulator 1 is to be
accelerated based on the reaction force acting direction memorized in the
storing section.

[0070]As described above, in the case where a reaction force by an inertia
force is determined to contribute to a collision avoiding operation,
based on the acceleration determining condition, the acceleration
determining section 25 determines "ACCELERATE AND PIVOTALLY MOVE". This
allows the control device 22 to accelerate the pivotal movement of the
arm 6, if the direction of the reaction force exerted on the centroid
position 4a of the arm 4 is determined to contribute to a collision
avoiding operation with respect to the obstacle 9. Specifically, a
reaction force in an obstacle avoiding direction can be utilized and
applied to the arm 4 in addition to a rotation torque in the obstacle
avoiding direction by the actuator 51. This enables to promptly avoid
collision with the obstacle 9.

[0071]Next, an operation to be performed by the manipulator 1 is described
referring to FIG. 7. FIG. 7 is a flowchart for describing an obstacle
avoiding operation to be performed by the manipulator 1 in accordance
with the first embodiment of the invention.

[0073]Then, the manipulator 1 causes the collision monitoring section 23
to monitor collision of the movable member 2, 4, 6 with the obstacle 9
(Step S102).

[0074]Then, the manipulator 1 determines whether or not there is a
possibility of collision of the movable member 2, 4, 6 with the obstacle
9, based on monitor information outputted from the collision monitoring
section 23 (Step S104). Specifically, since the collision monitoring
section 23 is activated in the case where there is a possibility of
collision of the movable member 2, 4, 6 with the obstacle 9, the
collision monitoring section 23 outputs monitor information to the
control device 22 in the case where there is a possibility of collision.
On the other hand, in the case where there is no possibility of collision
of the movable member 2, 4, 6 with the obstacle 9, the collision
monitoring section 23 is not activated, and the does not output monitor
information to the control device 22. Accordingly, the manipulator 1 is
operable to determine presence or absence of a possibility of collision
of the movable member 2, 4, 6 with the obstacle 9, based on monitor
information. In other words, Step S102 and Step S104 correspond to a
collision monitoring step of determining presence or absence of a
possibility of collision with respect to each of the movable members 2, 4
and 6.

[0075]The manipulator 1 controls the actuator 31, 51, 71, or the
moving/driving section 14 in such a manner as to move the movable member
2, 4, 6 in a direction of avoiding the obstacle 9 based on monitor
information, in the case where the collision monitoring section 23 is
activated (Step S106).

[0076]In performing the above operation, the acceleration determining
section 25 in the manipulator 1 specifies one of the four regions of a
relative coordinate system set with respect to the joint section 5, in
which the centroid position (e.g. the centroid position 4a of the arm 4
in the posture shown in FIG. 3A) of a movable member (e.g. the arm 4)
specified by the collision monitoring section 23 exists, based on the
angle θ defined by the arm 4 and the arm 6. Then, the acceleration
determining section 25 determines whether or not a reaction force acting
on the centroid position of the movable member (the arm 4) contributes to
a collision avoiding operation, in the case where the pivotal movement of
the other movable member (e.g. the arm 6) is accelerated, based on the
specified region in which the centroid position exists, pivotal direction
information of the other movable member (e.g. the arm 6), and positional
relation information on the positional relation between the movable
member (e.g. the arm 4) and the obstacle 9 (Step S108). Then, the
acceleration determining section 25 determines "ACCELERATE AND PIVOTALLY
MOVE", in the case where the reaction force generated by acceleration of
the other movable member (e.g. the arm 6) contributes to a collision
avoiding operation; and determines "DO NOT ACCELERATE AND PIVOTALLY
MOVE", in the case where the reaction force does not contribute to a
collision avoiding operation. In this example, the condition that a
reaction force acting on the centroid position of a movable member (e.g.
the arm 4) contributes to a collision avoiding operation corresponds to a
condition that a reaction force acting direction is aligned with a
collision avoiding direction with respect to the obstacle 9. Further, the
condition that a reaction force acting on the centroid position of a
movable member (e.g. the arm 4) does not contribute to a collision
avoiding operation corresponds to a condition that a reaction force
acting direction is aligned with a collision direction with respect to
the obstacle 9. In other words, Step S108 corresponds to an acceleration
determining step.

[0077]In the case where the acceleration determining section 25 has
determined "ACCELERATE AND PIVOTALLY MOVE", for instance, the manipulator
1 pivotally moves the arm 4 in a reverse direction (the direction of
arrow B) in the posture shown in FIG. 3B, and accelerates the pivotal
movement of the arm 6 by increasing a rotation torque of the actuator 71
in addition to the reverse pivotal movement (Step S110). As a result of
the above operation, the base end of the arm 4 is applied with a rotary
moment around the centroid position 4a by the accelerating operation of
the arm 6, in addition to the rotation force by the actuator 51. This
enables to promptly perform pivotal movement of the arm 4 in a direction
away from the obstacle 9. In other words, Step S110 corresponds to a
controlling step. Then, the manipulator 1 determines whether or not the
manipulator 1 has avoided collision with the obstacle 9 (Step S112). In
the case where it is determined that the manipulator 1 has failed to
avoid collision with the obstacle 9, the routine returns to Step S110 to
continue acceleration of the pivotal movement. If, on the other hand, it
is determined that the manipulator 1 has avoided collision with the
obstacle 9, the routine proceeds to Step S114.

[0078]After having performed the collision avoiding operation, for
instance, the manipulator 1 suspends the operation of the actuator 31,
51, 71, or the moving/driving section 14, and suspends the operation of
the movable section 91 (Step S114). In the case where a target position
is set, the operation of the movable section 91 may be performed again to
move the manipulator 1.

[0079]As described above, the manipulator 1 in accordance with the first
embodiment is advantageous in utilizing a reaction force by an inertia
force acting on a centroid of a movable member in addition to a driving
force of the actuator 31, 51, 71 in controlling the movable member
specified by the collision monitoring section 23 to perform an operation
of avoiding collision with an obstacle. Accordingly, it is possible to
realize an operation of promptly avoiding collision of the hand 2, or the
arm 4, or the arm 6 with the obstacle 9.

[0080]In the first embodiment, the manipulator has two arms i.e. the arms
4 and 6. The invention is not limited to the above. Alternatively, a
manipulator constructed in such a manner that three or more movable
members are interconnected to each other enables to obtain substantially
the same advantage as described above.

[0081]In the first embodiment, the moving section 13 is configured to be
movable relative to the holding section main body 8a. Alternatively, the
holding section 8 may be provided with a driving section such as wheels
and configured to be freely movable, and the movement of the holding
section 8 may be accelerated in performing a collision avoiding
operation. In the modification, the holding section 8 functions as a
movable member. In the modification, only one arm may be provided,
because the holding section 8 functions as a movable member.

[0082]Further alternatively, each of the joint sections 3, 5, and 7 may
have a clutch section and a switching section, as will be described later
in the second embodiment, and the clutch section of the joint section 5
may be controlled to be freely movable in e.g. performing an operation of
avoiding collision of the arm 4.

Second Embodiment

[0083]In the following, a manipulator 10 in accordance with the second
embodiment of the invention is described referring to FIGS. 8 through
10B. FIG. 8 is a schematic construction diagram of the manipulator 10 in
accordance with the second embodiment of the invention. FIG. 9 is a block
diagram showing a construction of the manipulator 10. FIGS. 10A and 10B
are schematic front views of the manipulator 10 for describing a
retracting operation to be performed by the manipulator 10. Hereinafter,
like elements as in the first embodiment are indicated with like
reference numerals.

[0084]In the manipulator 1 in accordance with the first embodiment, the
collision monitoring section 23 is provided, and a movable member (e.g.
the arm 4) having a possibility of collision is specified based on
monitor information of the collision monitoring section 23. Then,
collision between the specified movable member (e.g. the arm) and the
obstacle 9 is avoided by combining a rotation torque in an obstacle
avoiding direction exerted on the movable member, and a reaction force by
an inertia force acting on the movable member by an accelerating
operation of the other movable member (e.g. the arm 6).

[0085]In contrast, the manipulator 10 in accordance with the second
embodiment is provided with a collision detecting section 24 to be
described later. A movable member that has collided with an obstacle 9 is
specified based on detection information of the collision detecting
section 24, and an impact force to be exerted on the movable member
specified by the collision detecting section 24 is alleviated by
utilizing a reaction force by an inertia force. Accordingly, even if the
manipulator 10 has collided with the obstacle 9, an impact force
resulting from collision can be alleviated.

[0086]Firstly, a construction of the manipulator 10 in accordance with the
second embodiment is described referring to FIG. 8.

[0087]The manipulator 10 includes a movable section having a hand 2, an
arm 4, and an arm 6, joint sections 30, 50, and 70, and a holding section
8 for holding the movable section.

[0088]The hand 2 is interconnected to the arm 4 through the joint section
30. The arm 4 is interconnected to the arm 6 through the joint section
50. The arm 6 is interconnected to the holding section 8 for holding the
arm 6 through the joint section 70. The hand 2, the arm 4, the arm 6, and
the holding section 8 are pivotally interconnected to each other.

[0089]Contact sensors 41 and 61 for detecting contact with the obstacle 9
are respectively disposed on surfaces of the arms 4 and 6.

[0090]A pressure-sensitive sheet formed by printing an electrically
conductive and pressure-sensitive ink in a matrix pattern may be used as
the contact sensors 41 and 61. In this arrangement, the contact sensor 41
is operable to detect contact with the obstacle 9, based on a change in
the resistance of the pressure-sensitive sheet, in the case where the arm
4 is contacted with the obstacle 9, and a pressure is applied to the
pressure-sensitive sheet. Similarly, the contact sensor 61 is operable to
detect contact with the obstacle 9, in the case where the arm 6 is
contacted with the obstacle 9, and a pressure is applied to the
pressure-sensitive sheet.

[0091]The holding section 8 has a mechanism section 81 and a driving
section 82. The driving section 82 includes an input section 21 for
allowing a user to input an operation command, a collision detecting
section 24 for detecting collision with the obstacle 9, and a control
device 22. The control device 22 controls movements of the hand 2, the
arm 4, and the arm 6, based on operation command information acquired
from the input section 21, and detection information acquired from the
collision detecting section 24. The collision detecting section 24 is
connected to the contact sensors 41 and 61.

[0092]Next, a construction and an operation of the manipulator 10 are
described referring to FIG. 9. FIG. 9 is a block diagram showing a
construction of the manipulator 10 in accordance with the second
embodiment of the invention.

[0093]The control device 22 controls movements of the hand 2, the arm 4,
and the arm 6 in accordance with an operation command from the input
section 21. Further, the control device 22 drives actuator 31, 51, 71 to
be described later to retract a movable member that has collided with the
obstacle 9, based on detection information of the collision detecting
section 24. Further, the control device 22 is provided with an
acceleration determining section 25. The control device 22 determines
whether or not a reaction force by an inertia force acting on a centroid
of a movable member is to be utilized in retracting the movable member
from the obstacle 9 in accordance with a determination result by the
acceleration determining section 25.

[0094]The collision detecting section 24 specifies a movable member that
has collided with the obstacle 9, based on contact detection information
acquired from the contact sensor 41, 61; and outputs detection
information of the specified movable member to the control device 22. For
instance, the collision detecting section 24 detects that the arm 4 has
collided with the obstacle 9, when the contact sensor 41 has detected the
contact. Similarly, the collision detecting section 24 detects that the
arm 6 has collided with the obstacle 9, when the contact sensor 61 has
detected the contact.

[0096]The clutch section 32 selectively sets the actuator 31 to an
operative state where the power of the actuator 31 is transmitted to the
hand 2 through a speed reducer 38, and an inoperative state where
transmission of the power of the actuator 31 to the hand 2 through the
speed reducer 38 is blocked by activating/deactivating the switching
section 33. An example of the clutch section 32 is a pair of clutch
plates. An example of the switching section 33 is an electromagnet
operable to selectively set the paired clutch plates to a contact state/a
non-contact state by turning on/off the current supply. The "activated"
state of the switching section 33 is a state, wherein the paired clutch
plates is in a contact state by turning off the current supply, and the
"deactivated" state of the switching section 33 is a state, wherein the
paired clutch plates is in a non-contact state by turning on the current
supply. The clutch section 32 transmits the power of the actuator 31 to
the hand 2 through the speed reducer 38 by setting the paired clutch
plates to a contact state. On the other hand, the clutch section 32
blocks transmission of the power of the actuator 31 to the hand 2 through
the speed reducer 38 by setting the paired clutch plates to a non-contact
state.

[0097]Similarly, the clutch section 52 selectively sets the actuator 51 to
an operative state where the power of the actuator 51 is transmitted to
the arm 4 through a speed reducer 38, and an inoperative state where
transmission of the power of the actuator 51 to the arm 4 through the
speed reducer 38 is blocked by activating/deactivating the switching
section 53. Similarly, the clutch section 72 selectively sets the
actuator 71 to an operative state where the power of the actuator 71 is
transmitted to the arm 6 through a speed reducer 38, and an inoperative
state where transmission of the power of the actuator 71 to the arm 6
through the speed reducer 38 is blocked by activating/deactivating the
switching section 73.

[0098]In the above arrangement, in the case where the clutch section 32 is
in an inoperative state, the joint section 30 is brought to a pivotable
(free) state with respect to an external force. Similarly, in the case
where the clutch section 52 is in an inoperative state, the joint section
50 is brought to a pivotable (free) state with respect to an external
force, and in the case where the clutch section 72 is in an inoperative
state, the joint section 70 is brought to a pivotable (free) state with
respect to an external force.

[0099]An encoder 36 detects rotation information of a motor 34. The
control device 22 detects positions and postures of the hand 2, the arm
4, and the arm 6, based on the rotation information and speed reduction
ratios of the speed reducers 38; and controls operations of the hand 2,
the arm 4, and the arm 6.

[0100]The angle sensor 37 detects a posture and a movement of the hand 2
based on absolute joint angle information. Since transmission of the
power of the actuator 31 to the hand 2 is blocked when the clutch section
32 is in an inoperative state, it is impossible to detect a movement of
the hand 2 by the encoder 36. However, even in this case, the angle
sensor 37 is operable to detect a movement of the hand 2. Further, in the
case where the clutch section 32 is brought to an operative state again,
it is possible to correct the rotation information of the encoder 36 by
using the absolute joint angle information of the angle sensor 37.
Similarly, the angle sensor 57 detects a posture and a movement of the
arm 4 based on absolute joint angle information of the angle sensor 57,
and the angle sensor 77 detects a posture and a movement of the arm 6
based on absolute joint angle information of the angle sensor 77.

[0101]Examples of the angle sensors 37, 57, and 77 are a magnetic sensor
constituted of a hall element or a magnetic resistor element, and a
rotary magnet having a north pole and a south pole; and a potentiometer
based on a principle of a variable resistor.

[0102]Next, a retracting operation to be performed by the manipulator 10
is described referring to FIG. 9, and FIGS. 10A and 10B.

[0103]The control device 22 drives the actuator 31, 51, 71 in accordance
with an operation command from the input section 21, and acquires, from
the collision detecting section 24, detection information of a movable
member (the hand 2, or the arm 4, or the arm 6) which has contacted with
the obstacle 9. In the case where the collision detecting section 24 has
detected that a movable member has collided with the obstacle 9 based on
the detection information, the control device 22 starts an operation of
retracting the movable member from the obstacle 9, based on e.g. the
detection information of the movable member that has collided with the
obstacle 9, and driving information of the joint section 50, 70.
Specifically, the control device 22 generates control information for
retracting the movable member from the obstacle 9, and alleviating an
impact force resulting from collision; drives the actuator 31, 51, 71
based on the control information; and controls the joint section 30, 50,
70 to pivotally move the joint section 30, 50, 70.

[0104]As shown in FIG. 10A, the manipulator 10 drives the actuator 31, 51,
71 in accordance with an operation command from the input section 21. For
instance, the manipulator 10 suspends the operation of the actuator 31,
activates the switching section 33, 53, 73, and drives the actuator 51,
71. As a result of the above operation, for instance, the arm 4 is
pivotally moved in the direction of arrow A about an axis of rotation of
the joint section 50, and the arm 6 is pivotally moved in the direction
of arrow A about an axis of rotation of the joint section 70.

[0105]In the case where the arm 4 is contacted with the obstacle 9, the
contact sensor 41 is activated, and the collision detecting section 24
detects collision between the arm 4 and the obstacle 9, and outputs
detection information to the control device 22. The control device 22
sets the switching section 53, 73, and controls the actuator 51, 71 to
retract the arm 4 from the obstacle 9 based on the detection information.

[0106]Specifically, the control device 22 switches the switching section
53 from an activated state to a deactivated state, after having detected
collision between the arm 4 and the obstacle 9, and accelerates pivotal
movement of the arm 6 in the direction of arrow A by increasing a driving
force of the actuator 71. Specifically, the manipulator 10 accelerates
the pivotal movement of the arm 6 in the collision direction (the
direction of arrow A) with respect to the obstacle 9 in a state that the
joint section 50 is brought to a pivotable (free) state with respect to
an external force.

[0107]As shown in FIG. 10B, in response to acceleration of pivotal
movement of the arm 6 in the direction of arrow A about an axis of
rotation of the joint section 70, an inertia force acting on the arm 4 by
acceleration of the pivotal movement of the arm 6 is acted as a reaction
force, because the joint section 50 is brought to a pivotable (free)
state with respect to an external force. As a result of the above
operation, the arm 4 is pivotally moved in a direction (the direction of
arrow B) away from the obstacle 9 about the axis of rotation of the joint
section 50. Accordingly, upon collision, the posture of the arm 4 is
changed in the direction of arrow C, despite acceleration of pivotal
movement of the arm 6 in the collision direction with respect to the
obstacle 9, because a reaction force by an inertia force in the obstacle
avoiding direction is exerted on the centroid of the arm 4.

[0108]As a result of the above operation, the manipulator 10 is operable
to retract the arm 4 from the obstacle 9. Similarly, in the case where
the contact sensor 61 is activated, and the collision detecting section
24 has detected collision between the arm 6 and the obstacle 9, the
control device 22 drives the actuator 51, 71 in such a manner as to
retract the arm 6 from the obstacle 9.

[0109]As described above, similarly to the first embodiment, the
manipulator 10 in accordance with the second embodiment is advantageous
in retracting the arm 4 from the obstacle 9 by utilizing a reaction force
by an inertia force. Accordingly, even if an arm is collided with an
obstacle, an impact force resulting from collision can be alleviated.

[0110]The collision detecting section 24 does not output detection
information to the control device 22, as far as the contact sensors 41
and 61 do not detect contact (in other words, a state that both of the
arm 4 and the arm 6 do not collide with the obstacle 9). In this state,
the control device 22 activates the switching sections 53 and 73 to set
the clutch sections 52 and 72 the contact state. As a result of the above
operation, the manipulator 10 is operable to move the arm 4 and the arm 6
to respective predetermined positions in accordance an operation command
from the input section 21.

[0111]Further, in response to output of detection information from the
collision detecting section 24, a CPU accepts the detection information
by a hardware interrupt, and executes a program for performing a
collision avoiding operation. This is advantageous in enhancing the
response speed of the control device 22 when collision has occurred.

[0112]Furthermore, the manipulator 10 changes the pivotal direction of the
motor 34 in a reverse direction upon collision. Accordingly, for
instance, it is possible to retract the arm 4 from the obstacle 9 by
utilizing a reaction force by an inertia force in combination, in
retracting the arm 4 from the obstacle 9 that has collided with the arm
4. This is further advantageous in avoiding collision with the obstacle.

[0113]Alternatively, the manipulator 10 may use a collision monitoring
section 23 and the collision detecting section 24 in combination, and
utilize both of monitor information to be acquired from the collision
monitoring section 23 and detection information to be acquired from the
collision detecting section 24. This enables to perform an operation of
moving a movable member in the collision avoiding direction using the
monitor information before collision, in addition to an operation of
alleviating an impact force resulting from collision.

[0114]Further alternatively, as shown in FIG. 11A, movement of a moving
section 13 may be accelerated in response to detection of collision
between a movable member and the obstacle 9. Specifically, in the case
where the collision detecting section 24 has detected collision between
the arm 4 and the obstacle 9 in a condition that the centroid position 4a
of the arm 4 is located at a base end (on the side of the mechanism
section 81 with respect to X-X axis) with respect to the joint section
50, the manipulator 10 sets the switching sections 53 and 73 to a
deactivated state to bring the two joint sections 50 and 70 to a
pivotable (free) state with respect to an external force; and accelerates
the movement of the moving section 13 in the collision direction with
respect to obstacle 9. As a result of the above operation, as shown in
FIG. 11B, since the arm 4 can be retracted from the obstacle 9, an impact
force resulting from collision can be alleviated.

[0115]Further alternatively, the control device 22 may be provided with a
cooperation program for cooperating movements of the joint sections 30,
50, and 70 to operate the joint sections 30, 50, and 70 in cooperation
with each other by executing the cooperation program. This enables to
enhance the advantages of the collision avoiding operation and the impact
force alleviating operation.

[0116]In the second embodiment, the control device 22 detects positions
and postures of the hand 2, the arm 4, and the arm 6, based on rotation
information from the encoders 36 and speed reduction ratios of the speed
reducers 38 to control the operations of the hand 2, the arm 4, and the
arm 6. Alternatively, positions and postures of the hand 2, the arm 4,
and the arm 6 may be detected, using only absolute joint angle
information of the angle sensors 37, 57, and 77, to control the
operations of the hand 2 and the like, without using the encoders 36. In
the modification, it is possible to control the hand 2 and the like
without correcting angle information, even in the case where the clutch
sections 32, 52, and 72 are brought to an operative state after having
been brought to an inoperative state.

INDUSTRIAL APPLICABILITY

[0117]The invention is advantageous in controlling a manipulator, and
particularly useful as a manipulator to be used in a condition that
collision with an obstacle may occur, and a method of controlling the
manipulator.